The contractor serves a general Vaccine Evaluation Unit for the Development and Applications Branch, MIDP, NIAID. Phase 1 and 2 clinical studies will be performed in adult, adolescent and pediatric groups consisting of normal and "at risk" individuals. Correlates of immunity for various vaccine candidates will be studied. In addition to clinical trials, limited epidemiologic surveillance studies will be performed to determine the presence of infectious disease agents for which prevention studies are being designed. Examples of vaccines to be studied are: Haemophilus influenzae type b conjugates, group B meningococcal vaccine, hepatitis A and B vaccines, rotavirus vaccines, and new acellular pertussis vaccines. There is a possibility that vaccine candidates for HIV will undergo early phase 1 trials at this and other Vaccine Evaluation Units.